Alex Salmond is very, very keen to see David Cameron campaigning on the streets of Scotland.

An old Etonian, come up from London to tell the locals how to vote -- gifts like that don't fall into the First Minister's lap very often.

The Conservatives, Labour and Liberal Democrats insist it's not a crisis -- though cancelling Prime Minister's Questions to charge up to Edinburgh certainly looks like blind panic.

Messers Cameron, Clegg and Miliband say Scotland, not Westminster, is where they should be -- but it seems to have taken them an awfully long time to realise that.

Actually, most of us down here in London are guilty of the same crime as our political leaders - frankly we ignored the debate about Scottish independence for months, confident it simply wouldn’t happen.

The polls showed the gap between Yes and No narrowing, and we assumed they couldn’t possibly catch up in time -- and then they did.

It’s worth remembering that of the dozens of polls conducted during this campaign, one - just one - has put the Yes camp in the lead. Every other survey has pointed to a No.

But that one poll has proved enough to prompt a grand Westminster awayday -- a huge gamble, and evidence of how seriously the risk of Scottish independence is (some might say finally) being taken.

Until now the likes of David Cameron and Ed Miliband have been keen to avoid taking a direct role in the No campaign -- fearing it could look patronising and desperate.

Alex Salmond didn’t repeatedly challenge David Cameron to a debate out of some sense of constitutional propriety. He did it because he thinks the Prime Minister is toxic to many floating Scottish voters.

It's a view secretly shared by some in Whitehall, and now we get to find out if that's true.

It looks like a panic because it is a panic -- a Yes vote next week would instantly become the only thing this coalition government would be remembered for. David Cameron would be the man who lost the union, perhaps struggling to remain PM until next May's election.

He's already had to offer even more power to the Scottish Parliament in return for a no vote -- "no doesn't mean no change" -- and this is perhaps Alex Salmond's real victory.

If Scotland says Yes to independence next week, Mr Salmond has achieved his life-long dream. But if the decision is No, Scotland will become a more semi-detached part of the UK, in control of its own destiny to a great extent, further divorced from Westminster.

Those weakened ties mean the next time this question is asked, the outcome may not be on a knife-edge -- assuming today's trip to Scotland doesn't backfire, it's possible the best outcome will be delaying independence by just a couple of decades,